Airless spray guns have been sold and used for many years. Typical of such spray guns is the Silver Gun.TM. airless spray gun sold by Graco Inc., the assignee of the instant invention. The instruction form for that product, publication no. 307-046 is hereby incorporated by reference. The needle assembly in such guns is desirably designed for a long life and corrosion resistance and includes a ball seal and a ball retainer. The ball retainer has a needle attached via a set screw and the other end of the needle is retained by a needle clamp which also has a set screw.
A packing housing is located on the needle intermediate the two ends. A spring is contained between a packing retainer and the ball retainer. Because of the geometry of where the trigger of such spray guns contacts the needle, non-axial forces are imposed on the needle, and the needle can be prone to breakage prior to the seal or ball wearing out.